Traditional lavatories, such as bathroom sinks and the like, include a vent hole that connects to a drain pipe to prevent overflow of the lavatory. The vent hole also allows for air that is present in the drain pipe to exit through the vent hole as water enters the drain. Without proper venting of the lavatory, air can become trapped between the drain opening and the trap of the drain pipe. In this situation, the water level in the lavatory basin will either rise until the water pressure above the trapped air forces the air down the drain, or the lavatory overflows.
Recently, many lavatories have been built without a vent hole for aesthetic reasons. Venting in those lavatories is typically addressed by making the openings in the drain cover very large and/or designing the drain cover to have a convex shape (i.e., a dome shape). However, the aesthetics for the drain cover are severely limited because the drain cover shape and the openings of the drain cover are dictated by the venting/draining requirements of the lavatory. Moreover, the drain openings in most drain covers are fixed. Thus, conventional drain covers are not adapted for use across multiple lavatories having different venting/draining requirements.